feat(chat): live turn metrics — telemetry reducer + rendering

Consume wire/transport-contract 0.3.0 (step-complete event + timing
fields on usage/tool-result/done). Pure core/telemetry module:
foldMetricEvent (reducer) + derived selectors (stepTps, turnTps, etc).
TelemetryState is pure data, no active-turn tracking — consumers pass
turnId to selectors. ChatStore wires foldMetricEvent into handleDelta
and exposes telemetry + currentTurnId. ChatView shows step-metrics
footer (time/TPS/tokens) on assistant text bubbles and durationMs badge
on tool cards. New TurnSummary component renders turn-level stats
(wall-clock, tokens, steps, TPS) in a DaisyUI stats block. Extended
live-probe to verify telemetry events against bin/up (pending backend
restart). 336 tests, typecheck 0, biome clean, build ok.

1 files changed, 75 insertions, 0 deletions

diff --git a/src/features/chat/ui/TurnSummary.svelte b/src/features/chat/ui/TurnSummary.svelte
new file mode 100644
index 0000000..eedb0cc
--- /dev/null
+++ b/src/features/chat/ui/TurnSummary.svelte
@@ -0,0 +1,75 @@
+<script lang="ts">
+	import type { TelemetryState } from "../../../core/telemetry";
+	import {
+		stepCount,
+		totalInputTokens,
+		totalOutputTokens,
+		turnMetrics,
+		turnTps,
+	} from "../../../core/telemetry";
+
+	interface Props {
+		telemetry: TelemetryState;
+		turnId: string | null;
+	}
+
+	let { telemetry, turnId }: Props = $props();
+
+	function formatMs(ms: number): string {
+		if (ms < 1000) return `${Math.round(ms)}ms`;
+		const s = ms / 1000;
+		return s < 60 ? `${s.toFixed(1)}s` : `${Math.floor(s / 60)}m${Math.round(s % 60)}s`;
+	}
+
+	const stats = $derived.by(() => {
+		if (turnId === null) return null;
+		const metrics = turnMetrics(telemetry, turnId);
+		if (metrics === undefined) return null;
+
+		const items: { label: string; value: string }[] = [];
+
+		if (metrics.wallMs !== undefined) {
+			items.push({ label: "Turn", value: formatMs(metrics.wallMs) });
+		}
+
+		const outTokens = totalOutputTokens(telemetry, turnId);
+		const inTokens = totalInputTokens(telemetry, turnId);
+		if (outTokens !== undefined || inTokens !== undefined) {
+			const total = (outTokens ?? 0) + (inTokens ?? 0);
+			items.push({ label: "Tokens", value: total.toLocaleString() });
+		}
+		if (outTokens !== undefined) {
+			items.push({ label: "Output", value: outTokens.toLocaleString() });
+		}
+		if (inTokens !== undefined) {
+			items.push({ label: "Input", value: inTokens.toLocaleString() });
+		}
+
+		const count = stepCount(telemetry, turnId);
+		if (count > 0) {
+			items.push({ label: "Steps", value: String(count) });
+		}
+
+		const tps = turnTps(telemetry, turnId);
+		if (tps !== undefined) {
+			items.push({ label: "TPS", value: `${Math.round(tps)} t/s` });
+		}
+
+		return items;
+	});
+</script>
+
+{#if stats !== null}
+	<div class="chat chat-start [&>.chat-bubble]:max-w-5xl">
+		<div class="chat-bubble w-full bg-transparent">
+			<div class="stats stats-vertical lg:stats-horizontal">
+				{#each stats as stat}
+					<div class="stat">
+						<div class="stat-title">{stat.label}</div>
+						<div class="stat-value text-sm">{stat.value}</div>
+					</div>
+				{/each}
+			</div>
+		</div>
+	</div>
+{/if}